CA1234156A - Process for producing 1,1,2,3-tetrachloropropene - Google Patents

Abstract

PROCESS FOR PRODUCING 1,1,2,3-TETRACHLOROPROPENE Abstract of the Invention A process is disclosed for preparing 1,1,2,3-tetrachloropropene comprising allylic rearrangement of 2,3,3,3-tetrachloropropene using a substantially anhydrous ferric chloride catalyst.

Description

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This application is a divisional of copending Application Serial No. ~58,213 filed July 5, 198~.

sackground of the Invention This invention relates to the preparation oE
1,1,2,3-tetrachloropropene and, more particularly, to a me-thod for such preparation involving 2,3,3,3-tetrachloropropene.
1,1,2,3-tetrachloropropene ("Tetra") is an impor-tan-t chemical intermediate useful, for example, in the preparation of the herbicide trichloroallyl diisopropyl thiocarbamate, commonly referred to as "triallate".
Conventionally, Tetra is produced by dehydrochlorination of l,1,2,2,3-pentachloropropane that is produced in turn by chlorination of 1,2,3-trichloropropene. While this process provides a generally satisfactory technical route, the cost of producing the tetrachloropropene depends upon the cost of -the trichloropropene raw material.
Smith U.S. patent 3,926,758 describes an altern-ative route to 1,1,2,3-tetrachloropropene in which 1,2,3-trichloropropane is chlorinated in an open vessel exposed to u.v. light to produce a mix of chlorinated products containing 20% to 60~ by weight unreacted 1,2,3-trichloropropane The chlorinator effluent is separated into five fractions, one of which contains 1,1,1,2,3- and 1,1,2,2,3-pentachloropropanes. Another fraction containing 1,1,2,3-tetrachloropropane is dehydrochlorinated and then rechlorinated to produce a further fraction containing 1,1,1,2,3- and 1,1,2,2,3-pentachloropropanes. These two pentachloropropanefractions are mixed and subjected to de-~r~

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hydrochlorination -to provide a mix of 1,1,2,3- and 2,3,3,3--te-trachloropropenes which is fed to an isomerizer packed with siliceous granules in which the 2,3,3,3-isomer is conver-ted to the 1,1,2,3-isomer.
U.S.S.R. Inventor's Certificate 899,523 describes a somewhat modified process in which 1,2,3-trichloropropane is chlorinated to produce tetrachloro propanes; 1,1,2,3- and 1,2,2,3--tetrachloropropanes are extracted from the reaction mixture and further chlori-nated in the presence of dimethylformamide as an initiator to produce pentachloropropanes; 1,1,1,2,3-and 1,1,2,2,3-pentachloropropanes are extracted from the pentachloropropane mixture and dehydrochlorinated to produce a mixture of 1,1,2,3- and 2,3,3,3-tetra-chloropropenes; and the latter mixture is boiled in the presence of aluminum oxide (at-tapulgite) to isomerize the 2,3,3,3- to the 1,1,2,3- isomer. An overall yield of ~8.19% is reported. The reference describes as prior ar-t a process very close to that of Smith.
An earlier xeference by Haszeldine, "Fluoro-olefins. Part II. Synthesis and Reaction of Some

3,3,3-Trihalogenopropenes" Journal of the Chemical Society [1953] pp. 3371~3378, describes a plethora of reactions of products derived from 1,1,1,3-tetra-chloropropane. The reference describes preparation of this intermediate by reaction of carbon tetra-chloride with ethylene in the presence of benzoyl peroxide. Among the numerous syntheses carried out by Haszeldine w~-th 1,1,1,3-tetrachloropropane as the starting material are: dehydrochlorination of this starting ma-terial with 10% ethanolic potassium hydroxide to produce a mixture of 3,3,3- and 1,1,3-trichloropropene; isomerization of 3,3,3-trichloro-~1 .

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propene -to 1,1,3-trichloropropene using a variety of allylic rearrangement catalysts including antimony fluoride, concentrated hydrochloric acid, concentrated sulfuric acid, aluminum chloride, ferric chloride, ethanolic KOH and anhydrous hydrogen fluoride; chloro-ination of 1,1,3-trichloropropene in the presence o~
llght to produce 1,1,1,2,3-pentachloropropane; chlori-na-tion of 3,3,3-trichloropropene to prod~ce 1,1,1,2,3-pentachloropropane; dehydrochlorination of 1,1,1,2,3-pentachloropropane with ethanolic potassium hydroxideto produce a mix-ture of 2,3,3,3-tetrachloropropene and 1,1,2,3-ke-trachloropropene; separation of 2,3,3,3-tetrachloropropene from 1,1,2,3-te-trachloropropene by distillation; and isomerization of 2,3,3,3-tetrachloro-propene in the presence of aluminum chloride to produce1,1,2,3--tetrachloropropene in 51% yield. Alternatively, Haszeldine discloses thermal isomerization of 2,3,3,3-tetrachloropropene to 1,1,2,3-tetrachloropropene at 180C in 45% yield. Based on the yields reported by Haszeldine for the above described series of steps, the overall yield obtained with his syntheses ca~ be computed as 41.8% based on 1,1,1,3-tetrachloropropane, 10.4% based on carbon tetrachloride.
Asahara et al., "The Telomerization of Ethy-lene and Carbon Tetrachloride", Kogyo Kagaku Zasshi 1971, 74(4), 703-5 discloses telomerization oE ethylene and carbon tetrachloride at 130C and at 60-70 x 105 Pa (60-70 a-tmospheres) pressure in the presence of a triethyl phosphite-ferric chloride hexahydrate catalyst to produce 1,1,1,3-tetrachloropropane. Takamizawa et al.
U.S. 4,243,607 describes an improvement in the Asahara ' :

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process whereby higher yields of l,1,1,3-tetrachloro~
propane are obtained by utilizin~ a catalyst system comprising a nitrile in addition to an iron salt and a -trialkyl phosphite.
Japanese Kokai 74-66613 describes a process for producing 1,1,3-trichloropropene by dehydrochlorina-tion of 1,1,1,3-tetrachloropropane using anhydrous FeC13 as a cata]yst. Reaction is carried out using 0.2 -to 0.6 g FeC13 per mole of 1,1,1,3-tetrachloropropane at a temp-erature of 80C to 100C.
A need has remained in the art for improved pro-cesses for the synthesis oE 1,1,2,3--tetrachloropropene, especially processes which provide this product in high yield using relatively inexpensive starting ma-terials and which can be operated at modest manufacturing cos-ts~
Summary of the Invention BrieEly, the present invention is directed to a process for producing 1,1,2,3-tetrachloropropene by con-tacting 2,3,3,3-tetrachloropropene with a catalytic proportion of substantially anhydrous ferric chloride, thereby effecting isomerization of the 2,3,3,3-tetra-chloropropene to 1,1,2,3-tetrachloropropene via an allylic rearrangement reaction.
More particularly, an optional feature of the invention is directed to a process for producing 1,1,2,3 tetrachloropropene as outlined above. This involves using a mixture of 1,1,2,3-te-trachloropropene and 2,3,3,3-tetra-chloropropene which is con-tacted with anhydrous ferric chloride, thereby eEfecting isomerization of the 2,3,3,3-isomer without substantially afEecting the 1,1,2,3-isomer initially present or produced from the 2,3,3,3-isomer.
In a preferred embodiment, the above process is carried out using the isomer mixture which is mixed with between about 5 ppm and about 50,000 ppm by weight oE
Eerric chloride. The isomer mixture may be subjected to azeotropic distillation after addition of ferric chloride ,~P~

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to thereby substantially remove any water of hydration from the Eerric chloride and any free water Erom the system.
The isomer mixture may be prepared by dehydrochlor-ination of l,1,1,2,3-pentachloropropane, which dehydro-chlorination is preferably by contacting the 1,1,1,2,3-pentachloropropane with a base in -the presence of a phase transfer ca-talyst at a tempera-ture of between about 50C
and about 110C.
1,1,1,3-tetrachloropropane can be deydrochlorinated to produce a mixture of 1,1,3-trichloropropene and 3,3,3-trichloropropene, and the preparation of -the 1,1,1,2,3-pentachloropropane can be achieved by chlorinating at least one of the trichloropropenes obtained by the dehydro-chlorination of 1,1,1,3-tetrachloropropane. The 1.,1,1,2,3-pentachloropropane can be prepared by chiorinating the mixture oE trichloropropenes. The mixture of 1,1,3- and 3,3,3-trichloropropenes may be contacted with a catalyst, with the 3,3,3-trichloropropene, and the 1,1,1,2,3-pentachloropropane being prepared by chlorinating the trichloropropene after the isomerization.
The above mixture of trichloropropenes can be distilled to separate the 1,1,3-trichloropropene from 3,3,3-trlchloropropene, with the preparation of 1,1,1,2,3-pentachloropropane being carried out by chlorinating at least one of the trichloropropene fractions obtained by the distillation. If desired, the 1,1,1~3-tetrachloropropane can be dehydrochlorinated by contacting the 1,1,1,3-tetrachloropropane with a base in the presence of a phase transfer catalyst at a temperature of between about 40C
and about 80C.
The 1,1,1,3-tetrachloropropane can also be prepared by reacting carbon tetrachloride and ethylene i.n the presence of an active source of metallic iron and a promoter for the : reac-tion, with the promoter being selected from the group consisting of trialkyl phosphi-tes and phosphorus (V) : compounds containing a phosphoryl group.

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Description of the ~referred Embodiments __ In accordance with the present invention, a novel process has been discovered by which l,1,2,3-tetra-chloropropene (Tetra) can be produced with significantly lower manufac-turing costs than have been attainable with previously known commercial processes. Moreover, the process of -this invention provides improved efficiency and yields as compared to other known prior art processes based on l,1,1,3-tetrachloropropane. l,1,2,3-tetrachloro-propene produced in accordance with the process of theinvention is of high ~uality, suitable for use in manu-facture of herbicides, pharmaceuticals and other end products.
As noted above, the l,1,1,3-tetrachloropropane can be prepared by reacting ethylene with carbon tetrachloride in the presence of both a source of metallic iron that is effective as an activator for the reaction, and a promoter for the reaction. According to a preferred embodiment, a reaction system is prepared comprising a liquid phase in contact with the source of metallic iron, the liquid phase comprising carbon tetrachloride and a promoter compatible therewith. Preferably, the promoter comprises a phosphorus (V) compound containing a phos-phoryl group such as, for example, an alkyl phosphate, alkyl phosphonate, phosphoryl chloride, or phosphorus pentoxide. Trialkyl phosphates such as triethyl phosphate and tributyl phosphate are most preferred. Other particular phosphorus (V) compounds which can be used as the promoter for the reaction include dimethyl methylphos-phonate, diethyl methylphosphonate, phenyl ethylphos-phonate, phenyl butyl phosphate, dimethyl phenyl phos-phate, and the like. Alternatively, but less preferably, a trialkyl phosphite such as triethyl phosphite or tri-butyl phosphate may be used as -the phosphorus compound promoter for the reaction between ethylene and carbon -tetrachloride. It has been found that higher productivity and yields are obtained with a trialkyl phosphate promoter ~3~56 -7- 09-21(2224)~
as compared to trialkyl phosphite. Quality of -the product is also generally better, and the reaction conditions less corrosive to process equipment.
A source oE metallic iron effective as an activator for the reaction is necessary, along with the phosphorus promoter compound, to effect reaction of carbon tetra-chloride ~ith ethylene to produce the 1,1,1,3-tetrachloro-propane with high selectivity, high yield and high product-ivity. Because the reaction is approximately first order with respect to the contact surface between the liquid phase and the source of metallic iron, it is preferred that iron sources having relatively large surface areas be used.
Various sources of metallic iron can be used in the reac--tion, with carbon steel and wrought iron being preferred.
Carbon steels are particularly advantageous. Cast iron is also suitable. Useful forms of the iron source include iron bars, rods, screens, filings, powder, sheets, wire, tubes, steel wool, and the like.
In order to maximize the selectivity of the reaction, it is further preferred -that the liquid phase contain ferric chloride at the outset of the reaction. This can be achieved by either adding ferric chloride to the system or generating it ln situ by heating the carbon tetrachloride in the presence of metallic iron and the promoter, prefer-ably at about reaction temperature, prior to introductionof ethylene. Although not limited to a par-ticular theory, it is believed that carbon tetrachloride is split into a trichloromethyl free radical and a chloride ion ligand by a redox transfer with ferrous ion, thereby producing a ferric ion to which the ligand is attached. It is ~Eurther believed that the metallic iron serves as a source of ferrous ions -that participate in the postulated redox transfer wi-th carbon tetrachloride, and that the promoter is instrumental in the oxidation and dissolution of the metallic iron. Dissolution of metallic iron results in the Eormation of ferrous ions, either directly or by reduction ~3~

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of ferric ions in the liquid phase. ~eaction of ethylene with -the trichloromethyl radical produces a trichloropropyl radical that ln turn condenses with the chloride ion ligand in a Eurther redox transEer in which ferric ion is reduced to Eerrous. Al-though ferric ion is thus produced in the course of the reaction by oxidation oE ferrous ion, an initial concentra-tion of ferric ion is useful in minimizing the formation of undesired by-products during -the early stages of the reaction.
Where a phosphorus (V) compound is used as the prom-oter, it is also preferred -that the Eerric chloride be substantially anhydrous and that the reaction system be maintained substantially free of water throughout the reaction. In such systems, the presence of appreciable proportions of water significantly retards the reaction rate. However, where the promoter is a phosphite such as triethyl phosphite or tributyl phosphite, the presence of modest amounts of water is not disadvantageous. In fact, minor proportions of water, up to an amount stoichio-metricly equivalent to the phosphite compound, may be use-ful in increasing the reaction rate. This may be due to the conversion oE phosphites to phosphates and/or phosphon-ates, and the attendant formation of HCl in the case of phosphate formation, by reaction with carbon tetrachloride.
In carrying out the first step of the above synthesis, ethylene is in-troduced into the carbon tetrachloride liquid phase containing the phosphorus compound, and pref-erably ferric chloride, in the presence of a source of metallic iron at a kempera-ture o-E 50C to 150C, preferably 70C to 130C. As noted, the ferric chloride may be initi-ally added as such or generated ln situ by heating the CCl4-promoter-Fe metal system prior to introduction of ethylene. Ethylene pressure is not narrowly critical.
Typically, ethylene can be introduced at a gauge pressure of between about 1 x 105 Pa and about 14 x 105 Pa (about l and about 14 atmospheres). It has further been -Eound ~23~5~
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desirable to have a relatively high ratio of ferric iron concen-tration -to ethylene partial pressure. ~owever, it is also important to maintain a molar excess of phosphorus compound with respect to ferric ion, since otherwise the reaction may stop. This is believed to result from the Eormation of a reaction product or l:l complex o phos-phorus compound and iron ion. ~lthough such reaction product or complex may still be active as a source of ferric ion for limiting the forma-tion of n ~ 2 telomer-iza-tion products, it appears to be inactive as a promoter for initiating the reac-tion. Preferably, therefore, -the reactor charge should initially contain between about 0.1 mole ~ and about 5 mole ~ of the phosphorous compound and between 0 and about 2 mole % ferric chloride based on carbon tetrachloride. Progress of the reaction depends on maintaining a supply of both free phosphorus compound and metallic iron throughout the reaction period. In order to assure the continued availability of phosphorus compound and metallic iron, it is, therefore, necessary to control not only the initial phosphorus compound and ferric chlor-ide content, but also the overall quantity of metallic iron ; available for dissolution and also the area of contact between the liquid phase and the source of metallic iron.
Intensity of agitation also afEects this balance.
For any given system, those skilled in the art may readily arrive at an appropriate combination of these para-meters. Preferably the system is operated with vigorous agitation and contains a quanti-ty of iron sufficient to provide for several batches (or several multiples of residence time in a continuous sys-tem) without significant variation in surface area. This system both provides high productivity and facilitates maintenance of an effec-tive supply of both phosphorus compound and metallic iron.
Further disclosure relevant to the preparation of 1,1,1,3-tetrachloropropane is set forth in the copending application of Scott S. Woodard, filed on even date here-with under Serial No. ~58,215.

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Where the reaction of ethylene and carbon tetra-chloride is ca-talyzed or promoted by a phosphorus (V) compound such as a trialkyl phosphate, in most instances the liquid product is substantially a single phase material containing a high proportion of 1,1,1,3-tetrachloropropane and can often be -Eed directly to the next s-tep of the synthesis without further separation or purification. In the second step, the 1,1,1,3-tetrachloropropane is dehydro-chlorinated by contacting it with a base, preferably an aqueous caustic solution, in the presence of a phase transfer catalyst. PreEerably, the strength of the caustic solution is between about 15% and about 50% by weight.
Phase transfer catalysts useful in this reaction are known to the art. For example, various quaternary ammonium and quaternary phosphonium salts can be used to promote this dehydrochlorination step. The dehydrochlorination is preferably carried out by slowly adding the caustic solution to 1,1,1,3-tetrachloropropane con-taining the phase transfer catalyst while agitating the reaction mixture at a 20 temperature of 40C to ~0 C, preferably 50C to 75C.
~fter addition of the caustic solution is complete, the mixture is stirred for an additional period at reaction : temperature and then cooled. The aqueous phase is separ-ated and discarded. The organic phase containing a mixture 25 of 1,1,3- and 3,3,3-trichloropropene may then be used directly.
The trichloropropene mixture can be chlorinated, preferably in the presence of ultraviolet light to produce 1,1,1,2,3-pentachloropropane. Chlorine gas may be intro-duced either above the liquid sur-Eace or through a dip pipe and sparger Chlorination temperature is not cri-tical but may typically range from -10C to 80C, preferably 0C to 65C. PreEerably the isomeric mixture o:E 1,1,3- and 3,3,3-: trichloropropenes is chlorinated direc-tly to produce 1,1,1, 2,3-pentachloropropane. ~lternatively, the trichloropro-pene isomers can be separated prior to chlorination of one ~`~

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or both of them, or the 3,3,3-isomer component thereof first converted to the 1~1,3-isomer by contact with a Lewis acid allylic rearrangemen-t catalyst. If FeC13 is used for the rearrangement reaction, it should be removed prior to chlorination, as by distilling the isomerized material or extracting -the FeC13.
As disclosed in above SN 458,215, 1,1,1,2,3-penta-chloropropane can be converted to an isomeric mixture of 2,3,3,3- and 1,1,2,3-tetrachloropropene by dehydrochlor-ination with a base, preferably an aqueous caustic sol-u-tion, in the presence of a phase transfer catalyst.
Generally, the catalyst and caustic strengths used in this step may be approximately -the same as those used in the dehydrochlorination of 1,1,1,3-tetrachloropropane.
Caustic solution is added slowly to -the pentachloropropane containing the phase transfer catalyst. The temperature used in this step may be in the range oE 70C to 110C, preferably 80C to 100C. After all caustic is added, the reaction mixture is cooled, the phases separated and the aqueous phase discarded. The organic phase containing an isomeric mixture of 2,3,3,3- and 1,1,2,3-tetrachloro-propene may be distilled prior to -the isomerization step.
In carrying out the process of the present invention, an isomeric mixture of the tetrachloropropenes, or only the 2,3,3,3-tetrachloropropene is mixed wi-th a ferric chloride catalyst which effects rearrangement of 2,3,3,3-to 1,1,2,3-tetrachloropropene. However, if there is perceptible water in the isomerization mixture, as indicated, for example, by cloudiness or the presence of drops, or if a hydra-ted catalyst is used, the mixture is preferably subjected to azeotropic distillation to remove residual water. Isomerization may proceed concomitantly with moisture removal, accelerating as -the water content of the mixture declines. It is particularly preferred that the isomerization reaction be carried out using substantially anhydrous ferric chloride as the catalyst.

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It has been discovered that anhydrous ferric chloride catalyzes a very rapid allylic rearrangement of 2,3,3,3-tetrachloropropene to 1,1,2,3-tetrachloropropene without aEfecting the 1,1,2,3-lsomer initially present or formed in the rearrangement reaction. Moreover, the catalytic pro-portion of ferric chloride needed for the step is quite low, for example, as low a~ 5 ppm. Higher concentrations promote more rapid reaction, but concentrations above about 5~ by weight do not serve a useful purpose. In fact, where the 1,1,2,3-tetrachloropropene is used for the preparation of -triallate, relatively large proportions of FeC13 in the 1,1,2,3-tetrachloropropene, for example 500 ppm or more, may lead to formation oE ferric hydroxide which must be separated from the triallate. For this reason, FeC13 concentration for ca-talyzing the rearrangemen-t is prefer-ably limited to 5 ppm to 400 ppm. ~lso, because the rearrangement is highly exothermic, catalyst dosage and initial reaction temperature should be ad~usted to avoid an excessive temperature rise. Temperature increases of 80 C
or higher can be experienced. For this reason, a diluent may also be desirable, for example, a heel of product from a prior batch.
It has further been found that the 1,1,2,3-tetra-chloropropene produced in the isomerization step can be utilized directly without further puri-Eication in the synthesis of the herbicide triallate. Triallate is produced by reaction of l,1,2,3-tetrachloropropene with diisopropylamine, carbonyl sulEide and a base.
The Eollowing examples illustrate the above.

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Example 1 Carbon -tetrachloride (273 g), triethyl phosphate (4.05 g), ferric chloride (1.03 g), and two mild steel rods having a -total surface area o~ 26 cm2 were charged to a 300 ml Hastelloy C autoclave provided with an internal cooling coil. The au-toclave was thereaf-ter flushed twice with nitrogen and once with ethylene, pressurized with e-thylene to about 4.1 x 105 Pa gauge (4.1 a-tm gauge), and sealed. The mixture contained in the autoclave was s-tirred a-t 600 rpm and heated to 120C, a-t which temperature -the pressure was observed to be approximately 8.3 x 105 Pa gauge (8.2 atm gauge). As a result of the reaction of the carbon tetrachloride with the ethylene, the pressure in -the clave dropped rapidly.
Within one minute of reaching 120C, the ethylene feed valve was reopened and the autoclave pressurized to about 9.8 x 105 Pa gauge (9.7 atm gauge) and maintained there for 150 minutes. The reactor was then cooled and vented. A product mixture (327 g) was ob-tained. No tars or solids were produced. However, a slight second phase did separate upon standing. The product mixture was analyzed and found to contain 95.1% by weight of 1,1,1,3-tetrachloropropane. Only 0.4% carbon tetra-chloride remained. The yield based on carbon tetra-chloride initially present was 96.4%. The mild steel rods were weighed and it was de-termined that 0.54 g of iron had dissolved in the reaction mixture during the course o~ the reaction. A repeat of this reaction required 190 minutes to reach completion and the yield was 96.6%.

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Example 2 Carbon tetrachloride (806 g), triethyl phosphite (8.8 g), acetonitrile (2.16 g), and ferric chloride hex-hydrate (1.41 g) were charged to a one liter stalnless steel autoclave equipped with a stirrer, cooling coil and condenser. The au-toclave was flushed with nitrogen and then charged with ethylene -to a gauge pressure of about 4.8 x 105 Pa gauge (4.8 atm gauge) while stirring the liquid charge. The liquid con-tents oE the au-toclave were heated to 120C. As hea-ting -took place, the pressure rose to a peak of about 9.3 x 105 Pa yauge (9.2 atm gauge) and then began to drop as the temperature approached 120C.
When the temperature reached 120C, the autoclave was pressurized to about 9.8 x 105 Pa gauge (9.7 a-tm gauge) with ethylene and the reacting mixture maintained at 120C and stirred for six hours at that ethylene pressure.
After six hours the reactor was cooled, then ventedO
The li~lid product collected from the autoclave weighed 952 g, of which 887 g was identified as 1,1,1,3-tetra-chloropropane (93.1% yield). No unreacted carbon tetra-chloride was detected in the product, indicating a 100%
conversion. Slight tar formation on the reac-tor cooling coils was noted.

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Example 3 Carbon tetrachloride (278 g~, -triethyl phos-phate (4.05 g) and two mild steel rods having a total surface area of 26 cm were charged to a 300 ml Hastelloy C autoclave. The autoclave was thereaf-ter flushed twice with ni-trogen, then once with ethylene, pressurized with ethylene -to about 3.4 x 10 Pa gauge (3~4 atm gauge), and sealed. The mixture contained in the autoclave was stirred and heated to 120C at which -temperature the gauge pressure was observed to be approxima-tely abou-t 9.6 x 10 Pa gauge (9.5 atm gauge). As a result of reaction of the carbon te-trachloride with ethylene, the pressure in the autoclave then dropped rapidly and, when the pressure dropped below about 6.9 x 105 Pa gauge (6.8 atm gauge), the ethylene feed valve was reopened, the autoclave repressurized to about 6.9 x 105 Pa gauge (6.8 atrn gauge) and maintained at that pressure for a total of four hours. The reactor was then cooled and vented. The produc-t mixture (331 g) was analyzed and found to contain 93.5% by weight 1,1,1,3-tetrachloro-propane. Only 0.6% carbon tetrachloride remained. The yield based on the carbon tetrachloride initially present was 94.2%. The mild steel rods were weighed and it was determined tha-t 0.81 grams of iron had dissolved in the reacting mixture during the course of the reac-tion.

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Example 4 Carbon tetrachloride (265 g), triethyl phosphate (4.18 g), and two mild steel rods having a total surface area OI 26 cm2 were charged to the autoclave described in Example 1. The autoclave was -thereafter flushed three times wi-th nitrogen and sealed. The mixture contained in the autoclave was stirred at 600 rpm and heated to 120C, at which point the pressure was approximately 3.2 x 105 Pa gauge (3.2 atm gauge). Af-ter the mixture had been heated at 120C for 37 minutes, the ethylene feed valve was opened and the autoclave pressurized to 6.9 x 105 Pa gauge (6.8 atm gauge) and maintained at that pressure for 280 minutes. After 208 minutes of ethylene addition, 1.07 g of additional triethyl phosphate was charged to the autoclave, resulting in an increased reaction rate at that point, thereby effecting substantially complete reaction after a total of 280 minutes of e-thylene addition. the reactor was cooled and vented. A product mixture (317 g), similar in nature to that in Example l, was obtained. No tars or solids were produced. The product mixture upon analysis was found to contain 94.3%
by weight 1,1,1,3~tetrachloropropane. Only 0.4% carbon tetrachloride remained. The yield based on carbon tetrachloride initially presen-t was 96.2%. The mild steel rods were weighed and it was determined tha-t 0.95 g of iron had dissolved in the reac-tion mixture during the course of the reaction.

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Example S

1,1,1,3-te-trachloropropane (149 g; approximately 100% pure) and a te-traalkyl qua-ternary ammonium halide sold under the trade designation Aliquat 336 by General Mills (0.54 g) were charged -to a 500 ml ACE reactor having side indents and provided with a thermometer, mechanical stirrer and addition funnel. The addition funnel was charged with 50% sodium hydroxide solution (66.5 g) -that had been dilu-ted to approxima-tely 140 ml (approximately 20% caus-tic). The mixture in -the reac-tor was stirred and heated on a steam ba-th -to 65C. When the temperature reached 65C, slow addition of caustic solution was commenced and this addition was continued over a period of 70 minutes. During caustlc addition, the reaction temperature was main-tained at 67 + 2C. When addition of caustic was complete, the reaction mixture was stirred for an additional 36 minutes at 67C. Stirring was then s-topped and the mixture cooled. The aqueous phase was removed and the product organic phase de-termined to weigh 120 g, of which 55.1 g (51.8~ yield) was 3,3,3-trichloro-propene, 35.6 g (42.8% yield) was 1,1,3--trichloropropene, and 16.3 g was unreacted 1,1,1,3-tetrachloropropane (89.1%) conversion).
The organic phase obtained from the reaction was distilled to provide a mixture of 3,3,3- and 1,3,3-trichloropropene of about 98.8% puri-ty and containing a ratio of approximately 55 parts 3,3,3-isomer to 45 parts 1,1,3-isomer.

~3~5~
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Ex~mple 6 A por-tion of the mix-ture of 3,3,3- and 1,1,3-trichloropropene prepared in Example 3 (66.0 g) was charged to a three-neck 100 ml round bot-tom flask equipped wi-th a magne-tic s-tir bar, an ultra viole-t lamp and two gas ports. The flask was then placed on an ice bath and -the isomer mixture cooled to 0C.
While the contents of the flask were stirred and irradiated with ultra violet light, chlorine was fed into the flask via one of the gas ports a-t such rate that a small but detectable amount exited the other gas port. Exit flow was de-tected by use of a gas bubbler. The chlorine input port was above the li~uid surface. At in-tervals the reaction mixture was sampled to determine completeness of chlorination. Af-ter 36 minutes, all of both of -the trichloropropene isomers were consumed, yielding 1,1,1,2,3-pentachloropropane in essentially 100% conversion. 98.7 g of organics ; were collected from the flask of which 93O8 g (96.8%
yield) was 1,1,1,2,3-pentachloropropane.

Example 7 A 500 ml ACE reactor with side indents, equipped with a mechanical stirrer, addition funnel and thermome-ter, was charged with 1,1,1,2,3-pentachloro-propane (145 g; 97.~% pure) and Aliquat 336 (0.31 g).
The addi-tion funnel was charged with a 50% caustic solution (55.2 g) which had been diluted to a volume of approxima-tely 130 ml. The mixture contained in the reactor was s-tirred and hea-ted via a steam bath to a ~'~3~
-l9- 09-21(2224)A
temperature of 90C and held a-t 90 + 2C throughout the subsequen-t reac-tion. When the contents of the reactor reached 90C, slow addition oE caus-tic solution was commenced and continued over a period of two and one-half hours and then held for another one-half hour. The reaction mixture was cooled down, stirring terminated and the organic and aqueous phases separated. 118 g of organics was collected, of which 115 g (98.0% yield) was an isomer mixture of 2,3,3,3- and 1,1,2,3-te-trachloro-propene. No 1,1,1,2,3-pentachloropropane was detected in the collec-ted organic phase, indica-ting that the conversion was 100%.

Example 8 The organic phase produced in accordance with Example 5, comprising an approximately 55/45 mixture 2,3,3,3- and 1,1,2,3-tetrachloropropene and containing no visible water (no cloudiness or drops), was mixed with 0.17% by weight anhydrous ferric chloride. This mixture was heated at 103C for 15 minutes. Quantitative isomerization of 2,3,3,3- -to 1,1,2,3-tetrachloropropene was achieved.

~1 ~3~3~56 -20- ~ 09-21(2224)~

Example 9 ~ one li-ter round bottom flask equipped with a condenser and collector was;charged with a mixture containing approxima-tely a 45/55 ratio of 1,1,2,3-tetrachloropropene to 2,3,3,3-te-trachloropropene and 2.3 ml of a 1% aqueous ferric chloride solution. The mixture was hea-ted to reflux, and the wa-ter azeotroped into the collector. All organics collected were returned to the flask. Within minu-tes of reachin~ re~lux and removal of -the water, quantita-tive isomeriza-tion took place converting all of the 2,3,3,3-tetrachloropropene into 1,1,2,3--tetrachloropropene.

Example lO

A dry 100 ml round bottom flask equipped with a condenser and magne-tic stir bar was charged with 94.5 g of 1,1,1,2,3-pentachloropropane (92.~% pure) and 0.26 g of ferric chloride. The mixture was heated and stirred at 164C for 7 hours. HCl gas was evolved during the reaction and was absor~ed directly into water. After cooling down, 79.3 g of product mixture was obtained.
This was analyzed and found to contain 93.5% by weight 1,1,2,3-te-trachloropropene and 0.58% by weight starting material. This corresponds to conversion of 99.5% and an essentially ~uantitative yield.

~, i ~3~5~i -21- ~ 09-21(2224)A

As various changes could be made in -the above me-thods without depar-ting from -the scope of the invention, it is in-tended tha-t all ma-t-ter contained in the above description shall be interpre-ted as i.llustrative and not in a limiting sense.

Claims (13)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. A process for producing 1,1,2,3-tetrachloropropene comprising contacting 2,3,3,3-tetrachloropropene with a catalytic proportion of substantially anhydrous ferric chloride, thereby effecting isomerization of the 2,3,3,3-tetrachloropropene to 1,1,2,3-tetrachloropropene.

2. A process as set forth in Claim 1, wherein a mixture of 1,1,2,3-tetrachloropropene and 2,3,3,3-tetrachloropropene is contacted with anhydrous ferric chloride, thereby effecting isomerization of the 2,3,3,3-isomer without substantially affecting the 1,1,2,3-isomer initially present or produced from the 2,3,3,3-isomer.

3. A process as set forth in Claim 2, wherein said isomer mixture is mixed with between about 5 ppm and about 50,000 ppm, by weight ferric chloride.

4. A process as set forth in Claim 3, wherein said isomer mixture is subjected to azeotropic distillation after addition of ferric chloride, thereby substantially removing any water of hydration from the ferric chloride and any free water from the system.

5. A process as set forth in Claim 2, wherein said isomer mixture is prepared by dehydrochlorination of 1,1,1,2,3-pentachloropropane.

6. A process as set forth in Claim 5 wherein said 1,1,1,2,3-pentachloropropane is dehydrochlorinated by contacting the 1,1,1,2,3-pentachloropropane with a base in the presence of a phase transfer catalyst at a temperature of between about 50°C and about 110°C.

7. A process as set forth in Claim 5, wherein 1,1,1,3-tetrachloropropane is dehydrochlorinated to produce a mixture of 1,1,3-trichloropropene and 3,3,3-trichloropropene, and preparation of said 1,1,1,2,3-pentachloropropane comprises chlorinating at least one of the trichloropropenes obtained by said dehydrochlorination of 1,1,1,3-tetrachloropropane.

8. A process as set forth in Claim 7, wherein 1,1,1,2,3-pentachloropropane is prepared by chlorinating said mixture of trichloropropenes.

9. A process as set forth in Claim 7, wherein said mixture of 1,1,3- and 3,3,3-trichloropropenes is contacted with a catalyst, the 3,3,3-trichloropropene therein is isomerized to 1,1,3-trichloropropene and 1,1,1,2,3-pentachloropropane is prepared by chlorinating the trichloropropene after the isomerization.

10. A process as set forth in Claim 7, wherein said mixture of trichloropropenes is distilled to separate the 1,1,3-trichloropropene from 3,3,3-trichloropropene, and the preparation of 1,1,1,2,3-petachloropropane comprises chlorinataing at least one of the trichloropropene fractions obtained by said distillation.

11. A process as set forth in Claim 7, wherein said 1,1,1,3-tetrachloropropane is dehydrochlorinated by contacting the 1,1,1,3-tetrachloropropane with a base in the presence of a phase transfer catalyst at a temperature of between about 40°C and about 80°C.

12. A process as set forth in Claim 7, wherein said 1,1,1,3-tetrachloropropane is prepared by reacting carbon tetrachloride and ethylene in the presence of an active source of metallic iron and a promoter for the reaction.

13. A process as set forth in Claim 12, wherein said promoter is selected from the group consisting of trialkyl phosphites and phosphorus (V) compounds containing a phosphoryl group.